EightBall/eightballvmzp_a2e.S

20 lines
528 B
ArmAsm

;
; Apple II zero page is used for VM
; registers: evalptr, PC, SP, FP
; $80-$9a are used by cc65 ZP segment so avoid this range
; Zero-page usage is documented in:
; ProDOS 8 Technical Reference Manual Section A.4
; The upper half of ZP is generally used by BASIC only, so we can use it.
.exportzp _evalptr := $a0
.exportzp _pc := $a1
.exportzp _sp := $a3
.exportzp _fp := $a5
.exportzp _wordptr := $a7
.exportzp _byteptr := $a9
.exportzp _tempword := $ab
.exportzp _evalstack := $ad ; 32 bytes